Voltage-controlled oscillators (VCOs) are used in various applications, including in phase-locked loops (PLLs). A PLL may be formed, for example, by combining a VCO in a closed-loop with a phase detector, a charge pump, and a filter.
The frequency of the VCO output may be influenced by changes in power supply voltage. Such sensitivity of the VCO frequency to changes in power supply voltage may influence adversely the performance of the PLL. Hence, a voltage regulator may be used to regulate the power supply voltage to the VCO.